(a) Technical Field
The present invention relates to a polyolefin resin composition having increased surface scratch resistance. More particularly, it relates to a polyolefin resin composition having increased surface scratch resistance, impact resistance, rigidity and dimensional stability and thus being useful for automotive interior/exterior parts, and a plastic article prepared using the same.
(b) Background Art
Due to excellent moldability, impact resistance, chemical resistance, etc., as well as low specific gravity and manufacturing cost, polypropylene composite resins have been widely used in the manufacture of automotive interior/exterior parts requiring both safety and functionality, including bumpers, instrument panels, door trim panels and interior trims. However, the polypropylene resin compositions developed thus far are not immune to surface scratches or other appearance-related problems in an uncoated state.
At present, some automotive interior parts, e.g., instrument panels, door trim panels and interior trims, are produced by the mold-in-color (MIC) process requiring no coating after injection in order to reduce production cost. However, since the uncoated parts are very vulnerable to scratches, the surface of the molded parts are easily damaged or contaminated by the hands or shoes of the driver or passengers, resulting in poor appearance. Thus, the resin composition used for these automotive interior parts need to have improved impact strength, rigidity, scratch resistance and antistatic properties while satisfying both safety and sensibility requirements.
Currently, the bumper fascia, an automotive exterior part, is fabricated by injection molding followed by coating. During transportation for coating or other post-processing or during storage, the injection molded part may be scratched. The scratched portion tends to result in poor appearance even after paint coating. Also, since dust or other impurities are easily attached to the injection molded part due to static electricity, it is essential to clean the part prior to its coating.
Recently, research has been focused on an MIC bumper fascia requiring no paint coating in order to reduce production cost. For this purpose, impact resistance and weather resistance are basically required properties, and, in particular, superior scratch resistance and antistatic properties are required. The resin composition used for the automotive interior parts such as door trim, instrument panel, glove box or console also needs to have improved impact strength, scratch resistance and antistatic property while satisfying both safety and sensibility requirements. Thus, a resin composition having superior scratch resistance and mechanical properties that can be used for the automotive interior/exterior parts is greatly needed.
Although research has been consistently underway to develop resin compositions for automotive interior/exterior parts having superior scratch resistance, there has been still no substantial result reported. Korean Patent Application Publication No. 10-2005-0093186 describes a polypropylene resin composition having improved scratch resistance, comprising an inorganic filler, a rubber and a silicone resin. However, it does not exhibit satisfactory flexural modulus, tensile strength or scratch resistance enough to be used for automotive interior/exterior parts. Further, the added silicone resin tends to move toward the surface during molding, resulting in poor appearance such as stains or gas traces.
The inventors of the present invention have also invented a polyolefin resin composition having improved scratch resistance and a plastic article prepared using the same (Korean Patent No. 986,798). However, one noted disadvantage is that although the polyolefin resin composition is applicable to interior trims, it is inapplicable to instrument panels or door trim panels requiring stricter scratch resistance.
Accordingly, development of a polypropylene resin composition for automotive interior/exterior parts having an even more improved scratch resistance and exhibiting satisfactory impact resistance, rigidity and dimensional stability is an urgent task in the automotive industry.